The Letters of Peter

The two letters of Peter, towards the end of most modern versions of the Bible, are short pastoral letters intended to encourage Christians in strife and persecution and provide answers to a number of questions that would have arisen in the church late in the first century, questions such as "Is Jesus really going to return soon?"

The letters are apparently written in very different styles, with the first letter written in educated, sophisticated Greek.  Although both letters claim to be written by Peter, that authorship of the second letter has been disputed in various ways, over the centuries.  Both were late in being accepted into the New Testament canon.

One possible explanation for the Greek stylistic differences may be that the letters have different amanuenses, different secretarial scribes.  The first letter is written by a secretary, Silvanus, whose Greek is eloquent while the second letter, more hurried with sloppier Greek, might have been dictated to someone else or written by Peter himself, shortly before death.

I Peter, focuses on Christians, as aliens and strangers, living in the Roman Empire and their need to still live as citizens of an eternal kingdom.

I Peter has a strong emphasis on Old Testament passages, familiar to his readers, from Isaiah and Hosea and others. Even though his readers are probably Gentiles, they are surely familiar with the Old Testament passages and the passages are mentioned without reference.

An especially good reference is from overviewbible.com here.

Their are a number of online references on I Peter.  As always there are Wikipedia articles on I Peter and on the authorship of these letters (but note the alert at the top of that page.)

The second letter is from a man facing death, concerned about false prophets and the future of the church.  It is intended to confront falsehoods and reassure those who have given up on Jesus's return.

A good overview of the second letter is here.